Group transfer polymerization of acrylates is widely recognized as being capable of producing living polymers with controlled molecular weight and narrow molecular weight distribution and there are multiple publications setting forth such methods. The method generally includes the reacting of acrylic monomers, or mixtures of them, with initiators and a catalyst to obtain living polymers.
For example, in U.S. Pat. No. 4,414,372, issued Nov. 8, 1983 to Farnham, et al, there is disclosed the primary elements of a method to produce living polymers. The catalysts set forth in that patent for use in the method include co-catalysts which are a source of bifluoride ions HF2, to produce the polymers.
Preferred are the co-catalysts which include sources of fluoride, cyanide or azide ions, those suitable being Lewis acids, for example zinc chloride, bromide or iodide, boron triflouride, alkylaluminum oxide and alkylaluminum chlorides.
Most preferred catalysts are tris(dimethylamino)sulfonium biflouride, tetraalkylammonium bifluorides, tetraarylphosphonium bifluorides, bifluorides of the alkali metals, especially potassium, and ammonium bifluoride.
Another example of disclosure of a method can be found in U.S. Pat. No. 4,417,034, which issued Nov. 22, 1983 to Webster in which living polymers and their preparation from acrylic-type or maleimide monomers and organosilicon, tin or germanium initiators is shown. The disclosure in that patent relating to catalysts is nearly analogous to that of the '372 patent and does not bear repeating herein.
There is disclosed in U.S. Pat. No. 4,508,880, which issued Apr. 2, 1985 to Webster, the further preparation of living polymers. The disclosure in this patent is identical to that of the '034 patent, as the '880 patent is a continuation of the '034 patent, and therefore, does not bear repeating herein.
The essence of the disclosures in the above mentioned patents is summarized in a publication in Macromolecules 1984, 17, 1415 to 1417. This publication is important because it sets forth the details of the catalysts that have been found useful by the above-mentioned patentees. Thus, the article sets forth at page 1416, left hand column, at the bottom, that the catalysts have to be used at levels of about 10 to 20 mol % relative to monomer to achieve complete conversions of acrylates and methacrylates.